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[Aimhere]

Hi,

I am using Media Center 10 (10.0.129 currently) on my laptop, which uses an Athlon 64 3200+ desktop-replacement processor.  FYI, it also has 1GB of PC2700 DDR SDRAM, a 60GB 5400RPM hard disk, 64MB ATI Mobility Radeon 9600 Pro graphics, and C-Media AC'97 audio.  OS is Windows XP Professional SP1.  My problem is that the audio tends to hiccup (kinds sounds like it's looping for a fraction of a second) now and then while music is playing in MC.  It is worse when the visualizations are visible on-screen, but still happens when the visualizations aren't displayed at all (e.g. app is minimized).  I tried every combination of output settings (in Tools/Options.../Output)... WaveOut and Directsound, buffer-size adjustments, etc.  None of it seemed to help.  Also stopped or disabled all background apps, same difference.

What I ultimately found was that AMD's PowerNow feature (part of the Athlon 64) may be the cause.  My CPU's nominal clock speed is 2 GHz. but PowerNow reduces the clock speed when the system is idle or performing low-intensity tasks, so that most of the time, it's only running at 800MHz.  It only jumps up to the full 2 GHz when the CPU load rises above 70% or so (and even then, it seems to happen in intermediate stages like 833 MHz or 1600 MHz).  All of this is controlled by Windows' Power management settings (in Control Panel)... the normal "Portable/Laptop" setting enables the variable clock speeds, while the "Always On" profile runs the CPU at 2 GHz continuously.

With the power profile set to "Portable/Laptop", if I run an app to monitor the clock speed while Media Center is playing, it stays at 800 MHz most of the time but occasionally jumps to a higher speed, usually only for a second or so, before dropping back down.  It seems that the hiccups happen whenever the clock speed changes.   Somehow, the change in the clock speed interrupts Media Center's processing long enough to cause a glitch.  When I change the power profile to "Always On" and try again, the hiccups go away.  However, I prefer to use "Portable/Laptop" because it obviously uses less power (for longer battery life and less heat generated, not to mention prolonging the life of the processor).

Media Center is the only app I've noticed a problem with... for example, Winamp 5.x doesn't have any trouble (with or without visualizations active), and most games peg the CPU usage at 100% anyway so the clock speed never drops.  Mind you, I know Winamp uses totally different code, but their approach does seems to work better (and Winamp consistently uses less CPU than MC)... I vastly prefer Media Center's organization abilities, though!  Is there anything I can do to get Media Center to quit acting up, short of running in "Always On" mode all the time?

Aimhere

[Matt]

Interesting.

MC has a more sophisticated playback engine than Winamp since it's all 32-bit and supports more flexible stuff like stackable DSP's, cross-fading, silence suppression, and other goodies.  So, it may take a percent more CPU, but it's worth it in our opinon.

About your problem, is the difference that Winamp doesn't mind when the clock kicks up and down, or that it doesn't kick up and down?  Have you tried updating your soundcard driver?

Thanks Aimhere.

[Aimhere]

Hi,

Thanks for the reply, Matt.  To answer your question, Winamp doesn't hiccup at all during playback, no matter how I use it...

- maximized without visualization (just the spectum analyzer in the main window)
- maximized with various AVS visualizations in a window
- minimized
- fullscreen AVS visualizations at various screen resolutions
- other visualizations (e.g. Geiss)

In all cases, the CPU utilization (as reported in Windows Task Manager) of Winamp is only about 2-8% (typically 4%) without visualizations active, 70-85% with AVS active (windowed).  As I watch the CPU speed meter in my monitoring app, the Athlon 64 remains at 800MHz without visualizations, and jumps to 1.6GHz-1.8GHz when AVS visualizations are active.  Winamp does not seem to cause the CPU speed switching to jump up and down like Media Center does... it's a steady 800MHz without AVS, and with AVS, it remains at/near full-speed.  I can try to simulate the speed jumps by rapidly activating/deactivating visualizations, but Winamp never glitches.

Contrast this with Media Center:  CPU utilization 15-25% with no visualizations at all (and occasional hiccups), 40-90% with visualizations (and frequent audio hiccups), depending on the current visualization.  Meanwhile, CPU speed fluctuates between 800MHz and 833MHz without visualizations, and jumps between 800MHz and ~1.6GHz with any visualization.

It seems like Media Center's CPU usage is close enough to the borderline conditions, even without visualizations, to cause the CPU clock speed to momentarily spike, then drop back to 800MHz, and a glitch happens every time.  On the other hand, with visualizations active on-screen, the CPU usage is much higher--- but not high enough to keep the clock at 1.6GHz continuously, and again, when it drops back to a lower speed the audio hiccups.  As I watch Task Manger's performance graph, it seems that Media Center's CPU usage is a lot more "spike-ey" (or inconsistent) than Winamp's, with or without visualizations.  This inconsistency appears to be giving the AMD PowerNow fits, and it can't make up its mind about which clock rate to stay at.

So, to make a long story short, the clock kicks up and down with Media Center, but not with Winamp.  Mind you, I have all the latest drivers for my system (including the soundcard and the AMD PowerNow feature), and I'm not using anything fancy like synthesized 3D sound, just basic stereo.  FYI, my disk drives are using UDMA mode, so disk access doesn't seem to be a problem.

If I disable the AMD PowerNow feature by setting my Windows power management to "Always On" or "Home/Office Desk", the system runs at 2.0GHz continuously and the playback is far smoother.

I really hope I can get this resolved, it's driving me nuts.  I kind of created a workaround by adding Winamp to Media Center's "Play Now" menu... yeah, yeah, it's a copout, but what can I do...

aimhere

[Aimhere]

Hi Again,

Well, I've now found that even Winamp will hiccup on this system if visualizations are turned off.  Under these circumstances, the CPU remains at 800MHz.  Note that Winamp will NOT hiccup if any of its visualizations are visible, which seems to force the system to jump to 1.6GHz and stay there.  Compare this to Media Center, which hiccups with or without visualizations.  Also note that MC causes the CPU speed to fluctuate wildly between 800MHz and 1.6GHz depending on which visualization is active (Winamp's AVS keeps the system at a steady 1/6GHz).

I find that, if Windows xP is set to "Always on" in its Power settings, so that the CPU runs at 2GHz continuously, Winamp is butter-smooth yet MC still skips occasionally (regardless of visualizations).

Now, I've tried changing every setting I can find with regard to playback settings (buffer sizes, Waveout vs. DirectSound, etc.) in both programs, and can't get either one to be totally smooth at 800MHz.  I've also disabled all background apps, terminated other processes, updated the sound drivers, even turning down *video* acceleration (read somewhere that the video can interfere with audio).  The only thing that helps is to make sure the CPU *never* runs at 800MHz (either by setting the system power properties to "Always On" or, for Winamp, turning on visualization).

I should point out that this laptop has a C-Media AC'97 audio codec, which I believe does little to accelerate audio processing.  Could it be that 800MHz just isn't enough to play MP3 smoothly with AC'97?  Any other laptop users care to chime in at this point???

[JimH]

I wonder if the power saving mode could be shutting down the disk drive.

[Aimhere]

I wonder if the power saving mode could be shutting down the disk drive.

Nope, the hard disk spins continuously (I am testing on A/C power, and with the power profile set to "Always On", the hard disk will never shut off).   Even if the system was running on battery power, the hard disk timeout is far longer than the timeframe in which I am seeing the glitches.  And besides, Media Center still glitches even in "Always On" mode...

My desktop PC never has any problems, but of course it uses a desktop CPU and has no real power management going on.  More to the point, the desktop PC has an Audigy 2 card (which accellerates audio six ways from Sunday) versus the brain-dead AC'97 codec in the laptop.

I wish other users with laptop systems would read this thread and chime in with their thoughts, I could use some input...

Aimhere

[Robert Taylor]

I've had some problems with audio hiccupping on laptops when the Infra Red interface is enabled.

Try disabling Infra Red in the Device Manager and see what happens.

Of course, if you want to utilise the Infra Red port, and it's the cause, you're stuffed!!

Hope this helps...

[Aimhere]

I've had some problems with audio hiccupping on laptops when the Infra Red interface is enabled.

Try disabling Infra Red in the Device Manager and see what happens.

Of course, if you want to utilise the Infra Red port, and it's the cause, you're stuffed!!

Hope this helps...

Thanks, I'm trying it out now.  Still seems to hiccup at 800MHz.  But, I will keep testing...